The major focus of this grant remains the use of quantitative high resolution image analysis techniques for the study, analysis, and classification of sickle cell disease blood specimens with the aim of developing new features and providing information of clinical utility. There are three major specific aims. Specific aim l is to perform quantitative analysis and classification of red blood cells from AA, SS, AS, and SC individuals using a high resolution image analysis system. This includes: 1) the continued development of quantitative image analysis features which differentiate red cells from SS and SC individuals (and other variant forms of sickle cell disease) from those of AA and AS individuals; 2) the identification of subpopulations of cells from AA and SS individuals using clustering, partitioning and multivariate graphical techniques; 3) performing cross-sectional analysis of specific patient and cell subpopulations in statistically significant numbers; and 4) visually comparing cell images selected by their quantitative features. Specific aim II involves the study of quantitative high resolution image analysis features from specimens obtained longitudinally. This involves: 1) increasing the number of longitudinal specimens from patients followed through crisis, recovery, and steady state; 2) correlating image analysis features with clinical course, laboratory data, and genotype; 3) contrasting image analysis features in mildly affected and severely affected sickle cell patients; 4) quantitating the effects of drugs on red cells from patients enrolled in clinical drug trials; and 5) extending image analysis studies to mouse red blood cells from a transgenic mouse model of sickle cell disease. Specific aim III is to upgrade the image analysis system in support of the above studies. The results of this study may contribute new knowledge to the understanding of sickle cell disease as well as having utility in the monitoring of patients and testing of antisickling agents.